Nitric oxide (NO) is a gas that, when inhaled, acts to dilate blood vessels in the lungs, improving oxygenation of the blood and reducing pulmonary hypertension. Because of this, nitric oxide is provided in inspiratory breathing gases for patients with pulmonary hypertension.
Often, apparatuses used for nitric oxide delivery require a minimum flow of breathing gas in order to operate properly. As the flow rate of breathing gas decreases, it becomes difficult to accurately measure the breathing gas flow rate with current flow sensors and injector modules. In fact, some delivery apparatuses shut down automatically when there is not a sufficient flow of breathing gas to be measured accurately. When the supply of nitric oxide is abruptly cut off, patients may experience adverse effects such as worsening of partial pressure of oxygen in arterial blood (PaO2) and increasing pulmonary artery pressure (PAP).
Variability or irregularity in the flow from a support device such as a breathing gas delivery system may produce such low flow conditions, which may then result in shutdown of the inhaled NO delivery system or other NO delivery apparatus. Additionally, current inhaled NO delivery systems and other NO platforms cannot be used with gentle ventilation as gentle ventilation often requires lower flows then conventional ventilation. This can, again, result in shutdown of the delivery apparatus with resulting rebound hypertension and oxygen desaturation, which may result in adverse events as serious as death.
Therefore, there is a need to monitor and display the flow(s) from the NO delivery system to provide safe delivery of nitric oxide.